clarified example

this page used to say

`<li>{{#linkTo posts.post post}}{{post.title}}{{/linkTo}}</li>`

now it says

`<li>{{#linkTo photos.edit photo}}{{photo.title}}{{/linkTo}}</li>`

I first read this page in the late afternoon after many hours of work. I
found `posts.post post}}{{post.title` confusing, given that `post` can
be either a noun or a verb in the example (and given that it can also be
an HTTP verb).
Merge pull request #439 from gilesbowkett/links_example_clarity

clarified example